This invention relates generally to inking devices adapted for use with industrial chart recorders, and more particularly to self-contained devices of this type which can be readily disposed of after their intended period of use has expired.
In the past, various arrangements have been devised for enabling quick installation of a recording pen device on the actuator or writing arm of a chart recorder. Typically the body of the pen device was elongate, some having a longitudinal groove or recess which received the end portion of the pen arm. Normally the width of the groove was such that the arm could be merely slipped in place, thereafter being frictionally held by its engagement with the groove walls. Such grooves had to be of fixed width, molded or machined to close tolerances in order to assure a reasonably tight grip on the pen arm, yet one where interference would not occur. As a result, such devices had to be "tailored" to suit a particular type and size of pen or writing arm.
Still other constructions involved the use of integral plastic lugs protruding from the surface of the pen cartridge or body. The spacing of the lugs was such that the pen arm could be snapped or slipped into place between them, thereby securing together the two parts. This prior construction had the drawback that the lugs would break off; also, it suffered from the same disadvantage as pen bodies which had grooves, in that the tolerance on the spacing of the lugs was critical, and a particular pen body was normally useable with only one size or type of pen arm. Since chart recorders are manufactured by a number of different companies, there tends to be substantial variation in the dimensions of the pen arms associated therewith. This presented a problem in that a number of different pen cartridge types had to be available, in order to accommodate the different sizes and styles of chart recorders in the marketplace at any particular time. In addition, some replaceable pen cartridges were difficult to install and remove. Under such circumstances the likelihood of damaging the pen arm or bearings associated therewith was always present.